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City ants take the heat

February 28 2007

While Al Gore's film, An Inconvenient Truth, has generated greater awareness of global warming, most people remain unaware of the more rapid warming that has occurred within major cities. In fact, large cities can be more than 10 degrees hotter than their surroundings. These metropolitan hot spots, which scientists refer to as urban heat islands, can stress the animals and plants that make their home alongside humans. Until recently, biologists had focused so much on the effects of global climate change, that they had overlooked the effects of urban warming.

Now, an international team of biologists, led by Michael Angilletta of Indiana State University, has shown that city animals have been affected by urban heat islands. These researchers discovered that ants within South America's largest cityÃ¢â‚¬â€SÃƒÂ£o Paulo, BrazilÃ¢â‚¬â€could tolerate heat better than ants from outside this city. Their findings suggest that ants have adjusted their physiology in response to urban warming.

"We don't know whether this pattern will hold up for other species or other cities, but people should certainly be looking," said Angilletta, an Associate Professor of Ecology and Organismal Biology. "Ultimately, this research could help us to understand how species will respond to global climate change."

Working closely with geographers from Indiana State University's Center for Urban and Environmental Change, these biologists will soon determine whether urban warming has affected species in other major cities.

"We will quantify heat islands on the small scales that pertain to organisms, initially in Indianapolis and later in other major cities throughout the world," said Weng, an Associate Professor of Geography and Director of Indiana State's Center for Urban and Environmental Change.

"We will construct thermal maps using satellite images recorded over several years. These maps will enable us to assess the potential biological consequences of urban warming and identify suitable sites for future experiments," Weng said.

The study is published in PLoS ONE, the international, peer-reviewed, open-access, online publication from the Public Library of Science.

Story Highlights

An international team of biologists, led by Michael Angilletta of Indiana State University, has shown that city animals have been affected by urban heat islands. These researchers discovered that ants within South America's largest city-Sao Paulo, Brazil-could tolerate heat better than ants from outside this city. Their findings, published in the online journal PLoS ONE, suggest that ants have adjusted their physiology in response to urban warming.